Speaker : Julie DUQUE, Institute of Neuroscience, Université catholique Louvain
"Probing arousal causally with taVNS: from resting motor excitability to decision and movement"
Arousal is difficult to study causally in humans: most evidence rests on pupillometry, which tracks arousal as it fluctuates rather than manipulating it. Transcutaneous auricular vagus nerve stimulation (taVNS) changes this: neuroimaging and animal work indicate that it engages the ascending arousal circuitry, including the locus coeruleus, and brief four-second trains reliably evoke phasic pupil dilation. I will present a series of studies using this protocol to trace how such an engagement shapes behavior, from resting motor excitability to perceptual decision and online motor control.
At rest, with no task to perform, taVNS increased corticospinal excitability, but only while the stimulation was ongoing. During perceptual decisions, it improved accuracy without any cost in speed, and the benefit was larger in the conditions where performance was weakest, arising from more efficient evidence accumulation. During reaching movements, it did not strengthen corrective responses to mechanical perturbations across the board: its effect followed how much a deviation actually threatened the goal, extending even to a reflex component that is normally insensitive to it.
I will close with a reflection on what this tells us about the capacity of taVNS to recruit arousal, and about the role arousal plays in decision and movement.
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Conference location
Please join the conference in Paris Brain Institute auditorium.